Hybrid Bermudagrass plant named ‘Emerald Dwarf’

ABSTRACT

A hybrid Bermudagrass cultivar, named ‘Emerald Dwarf,’ is distinguished by greater rhizome development and rooting depth in conjunction with low surface stolon development. The cultivar is especially suited to golf greens.

Latin name of the genus and species of the plant claimed: Cynodondactylon×Cynodon transvaalensis hybrid.

Variety denomination: ‘Emerald Dwarf’ Bermudagrass.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct Bermudagrass plant.Bermudagrass (Cynodon spp. L. C. Rich) is one of the most important andwidely used warm-season turfgrasses. It is adapted to the warm- andsubtropical-climatic regions of the world. The turf-type Bermudagrassesare C₄, perennials that originated in southeastern Africa. The commonturf-type species of Cynodon include: Cynodon dactylon (L.) Pers. ordactylon Bermudagrass which is a tetraploid; and Cynodon transvaalensis(Burtt-Davy) or African Bermudagrass which is a diploid. The dactylonBermudagrasses as a group are characterized by a relatively coarse leafwidth and lower shoot density, while the hybrid bermudagrasses tend tohave narrower leaf width and higher shoot density. Both are relativelylow-growing via vigorous lateral stems, both rhizomes and stolons.

Putting greens in the warm, humid climatic regions of the United Statesare usually planted with Bermudagrass. Once, two Bermudagrass varietiesdominated use on putting greens: ‘Tifgreen (328),’ released in 1956 and‘Tifdwarf,’ released in 1965, but with the introduction of ‘Champion’ inthe late 1990s, the group of grasses often referred to collectively asUltradwarf Bermudagrasses have been the most widely used on greens forthe last 10 years. These grasses include ‘Champion’ (PP 9,888),‘Floradwarf’ (PP 9,030), ‘Mississippi Supreme’ (PP 11,781), ‘Tifeagle’(PP 11,163), and ‘Minverde’ (PP 12,084).

There are six basic components of turfgrass quality: (a) uniformity, (b)density, (c) texture, (d) growth habit, (e) smoothness, and (f) color.

The expectations of today's golfers for fast, smooth putting greens haveresulted in heights of cut which are significantly lower than they werein the past. A height of cut of ⅛″ was unheard of prior to the late1980's, yet it is now commonplace. A modern putting green cultivar mustbe able to withstand this height of cut in order to be successful. Whilethe Ultradwarf Bermudagrasses as a group do tolerate low greens heights,experience has shown that they can present unique challenges for thegolf course manager because of their growth habit. The aspects of thesegrasses' growth habit which are problematic include: very high shootdensity, lateral growth which is comprised almost entirely of stolons,and, shallow rooting, as shown by Table 1 below.

TABLE 1 Shoots, roots, stolons, and rhizomes for five Bermudagrasses*Shoots Roots Stolons Rhizomes Cultivar (No. in²) (mg) (mg) (mg)‘Champion’ 119 a  230 a 910  4 b ‘Floradwarf’ 80 bc  130 bc 780  0 b‘Miniverde’ 120 a  220 a 870 16 b ‘Tifeagle’ 92 b   100 c 730 18 b‘Tifdwarf’ 66 c  270 a 780 200 a  *planted 15 Apr. 1997 at the Texas A&MUniversity Turfgrass Field Laboratory in College Station, TX and sampledAug. 26, 1997

Some of the problems which have been associated with this growth habitinclude scalping, difficulty in moving water into the rootzone causingturf loss due to desiccation, severe disease outbreaks, difficulty inestablishing and transitioning from overseeding, thatch accumulation,severe “grain” or “stem displaysia”, and lack of recuperative potential.Many courses have replaced some of these Ultradwarf varieties with othergrasses after having significant difficulties managing them.

While it is important for a turfgrass selected for putting greens topossess the ability to withstand low greens heights, there has been apronounced desire among golf course superintendents to have a cultivarwith a growth habit which would allow it to tolerate low heights of cutwhile still responding to management practices which were successful onthe older varieties ‘Tifdwarf’ and ‘Tifgreen (328).’

BRIEF SUMMARY OF THE INVENTION

‘Emerald Dwarf’ Bermudagrass is a dwarf triploid hybrid Bermudagrass(Cynodon dactylon×Cynodon transvaalensis) that has the extraordinarymorphological characteristics of substantially greater rhizomedevelopment when compared in replicated studies with the closest knowncultivars of Cynodon spp. It also possesses a significantly greaterrooting depth and root mass by depth under putting greens maintenance.This grown habit allows it to tolerate very low heights of cut, yet itdoes so without the management difficulties that have been associatedwith ultradwarf Bermudagrasses. In addition, in comparison to ultradwarfbermudagrasses, ‘Emerald Dwarf’ has higher overseeding color andquality, better uniformity during transition of overseeded puttinggreens grasses, and higher percentage coverage of Bermudagrass duringthat transition. All of these characteristics make it an excellentquality surface for putting greens, bowling greens, cricket wickets,croquet courts, and lawn tennis courts.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

FIGS. 1-3 are close-up photographs of ‘Emerald Dwarf’, ‘Tifdwarf,’ and‘Tifeagle’ showing leaf morphology;

FIG. 4 is a photograph illustrating the comparative internode length of‘Emerald Dwarf,’ ‘Tifgreen (328),’ ‘Tifdwarf,’ and ‘Tifeagle’;

FIG. 5 is a close-up photograph of ‘Emerald Dwarf’ showing rhizomeformation in native clay soil;

FIGS. 6-9 are close-up photographs of ‘Emerald Dwarf,’ ‘Tifdwarf,’‘Tifgreen (328),’ and ‘Tifeagle,’ showing relative rhizome and stolonformation;

FIG. 10 is a close-up photograph of comparative plugs of ‘EmeraldDwarf,’ ‘Tifgreen’ (328), ‘Tifdwarf,’ and ‘Tifeagle,’ take 18 monthsafter planting;

FIG. 11 is a close-up photograph of comparative plugs of ‘EmeraldDwarf,’ ‘Tifdwarf,’ and ‘Tifeagle,’ take 30 months after planting;

FIG. 12 is a photograph of comparative plugs of ‘Emerald Dwarf,’‘Tifeagle,’ and ‘Tifdwarf,’ taken 30 months after planting illustratingcomparative root depths;

FIG. 13 is a photograph of comparative profiles of ‘Tifeagle,’ ‘EmeraldDwarf,’ and ‘Tifdwarf,’ taken 30 months after planting, illustratingrhizome formation;

FIG. 14-15 are photographs of rhizomes collected from samples of‘Emerald Dwarf’ and ‘Tifdwarf’;

FIGS. 16-18 are close-up photographs of sample columns of ‘Tifeagle,’‘Tifdwarf,’ and ‘Emerald Dwarf’ illustrating the location of rhizomes inthe columns;

FIG. 19 is a close-up photograph of ‘Emerald Dwarf,’ ‘Tifdwarf,’ and‘Tifeagle’ showing relative leaf lengths; and

FIG. 20 is a close-up photograph of ‘Emerald Dwarf’ illustrating smallvegetative shoots produced by the seeds while they are attached to theseedhead.

DETAILED BOTANICAL DESCRIPTION

Origin of the Cultivar

The genotype ‘Emerald Dwarf’ is new and distinct natural turfgrassselection from a segregated patch found on a putting green in Houston in1992. The putting green had been originally planted with ‘Tifdwarf’hybrid Bermudagrass (Cynodon dactylon×Cynodon transvaalensis) in theearly 1970s. The grass was propagated from a single sprig in one-gallonpots at patentees Bay City, Tex. facility. It was then further cut intoindividual sprigs and planted in trays, and a 20,000 sq. ft. area wasthen planted in trays. This was then propagated into a 1.2 acre growtharea. A short lateral stem with a single node was used for asexualvegetative propagation and increase of the original source of ‘EmeraldDwarf’.

Taxonomy

‘Emerald Dwarf’ is a triploid, hybrid Bermudagrass (Cynodondactylon×Cynodon transvaalensis).

Morphological Characterization

Compared to other Bermudagrass cultivars, ‘Emerald Dwarf’ has theadvantageous morphological characteristics of high rhizome productionand relatively high rooting depth and mass, in conjunction with lowsurface stolon development. In addition, ‘Emerald Dwarf’ has improvedoverseeding color and quality, greater uniformity during transitionperiods, and greater coverage of Bermudagrass during transition overother ultradwarf Bermudagrasses. Applicants choose to describe the colorcharacteristics of the ‘Emerald Dwarf’ with reference to the RoyalHorticultural Society's color numbering system (“R.H.S. Color Chart”).

Compared to ‘Tifgreen 328,’ ‘Emerald Dwarf’ has greater shoot density,greater rhizome development, darker green color described by the R.H.S.Color Chart as R.H.S. 138A, medium light green, smaller leaf morphology,tighter internode length, and fewer seed heads.

Compared to ‘Tifdwarf,’ ‘Emerald Dwarf’ has similar shoot density, leafmorphology, and seedhead production, but has substantially greaterrhizome development, a substantially greater ratio of rhizomes tostolons, and significantly deeper rooting depth. Unlike ‘Tifdwarf,’‘Emerald Dwarf’ does not exhibit short day-length senescences (openingcanopy in fall), and does not form a thick mat of stolons near thesurface.

Compared to ultradwarf Bermudagrasses, ‘Emerald Dwarf’ has a lower shootdensity, substantially greater rhizome development, substantiallygreater root mass and diameter, less thatch production, substantiallygreater rooting depth, and is much more tolerant of heavy verticalmoving. ‘Emerald Dwarf’ has fewer and larger lateral stems thanultradwarf Bermudagrasses. Unlike ultradwarf Bermudagrasses, ‘EmeraldDwarf’ does not form a thick mat of stolons near the surface, naturallyforms a firm surface which is not prone to scalping, and does not formgrain or “sheen.” ‘Emerald Dwarf’ does not substantially restrict waterinfiltration into the rootzone, allowing for infrequent, deep wateringcycles.

This new and distinct combination of morphological characteristics hasbeen retained through succeeding multiple generations of asexualvegetative propagation. These traits render ‘Emerald Dwarf’ particularlysuitable for golf greens.

Leaf Blade Width

Quantitative assessments of leaf blade widths revealed ‘Emerald Dwarf’to have a mid-range leaf blade width and allied fine turf canopytexture. The leaf blade width of ‘Emerald Dwarf’ was found to besignificantly more fine than two hybrid Bermudagrass cultivars, being13.3% less than ‘Tifgreen’ and 8.2% less than ‘Tifdwarf’ (see Table 2),and significantly less fine than one hybrid Bermudagrass cultivar, being18.1% more than ‘Tifeagle.’

TABLE 2 Leaf Blade Width* Comparisons Among Four Bermudagrass (Cynodonspp.) Genotypes Leaf Blade Genotypes Width (mm) ‘Emerald Dwarf’ 1.3‘Tifgreen (328)’ 1.5 ‘Tifdwarf’ 1.4 ‘Tifeagle’ 1.1 *Measured at themidpoint length of the youngest, fully expanded leaf blade on a shoot,with six blade measurements per replicate container.Leaf Blade Length

Quantitative assessments of leaf blade lengths revealed ‘Emerald Dwarf’to have a mid-range leaf blade length. The leaf blade length of ‘EmeraldDwarf’ was found to be significantly longer than two hybrid Bermudagrasscultivars, being 46.4% more than ‘Tifeagle’ and 10.8% more than‘Tifdwarf’ (see Table 3) and significantly shorter than another hybridBermudagrass cultivar, being 37.9% less than ‘Tifgreen (328).’ FIG. 19is a photograph showing a comparison of the leaf lengths of ‘EmeraldDwarf,’ ‘Tifgreen (328),’ ‘Tifdwarf,’ and ‘Tifeagle.’

TABLE 3 Leaf Blade Length* Comparisons Among Four Bermudagrass (Cynodonspp.) Genotypes Leaf Blade Genotypes Length (mm) ‘Emerald Dwarf’ 16.4‘Tifgreen (328)’ 26.4 ‘Tifdwarf’ 14.8 ‘Tifeagle 11.2 *Measured on thethird leaf from the end of the stolon, with six blade measurements perreplicate container.Internode Length

Quantitative assessments of internode lengths revealed ‘Emerald Dwarf’to have a mid-range internode length. The internode length of ‘EmeraldDwarf’ was found to be significantly longer than two hybrid Bermudagrasscultivars, being 9% more than ‘Tifdwarf’ and 40.4% more than ‘Tifeagle’(see Table 4) and significantly shorter than another hybrid Bermudagrasscultivar, being 65.8% less than ‘Tifgreen (328).’ FIG. 4 illustrates thecomparative internode length of ‘Emerald Dwarf,’ ‘Tifgreen (328),’‘Tifdwarf,’ and ‘Tifeagle.’

TABLE 4 Internode Length* Comparisons Among Four Bermudagrass (Cynodonspp.) Genotypes Internode Length Genotypes (mm) ‘Emerald Dwarf’ 14.6‘Tifgreen (328)’ 22.2 ‘Tifdwarf’ 13.4 ‘Tifeagle’ 10.4 *Measured betweenthe third and fourth node from the terminal end of the stolon, with sixblade measurements per replicate container.Rhizomes vs. Stolons After 18 Months

Quantitative assessments of the number of rhizomes and stolons underputting greens maintenance after 18 months revealed ‘Emerald Dwarf’ tohave a comparatively high rhizome to stolon ratio. The rhizomepercentage of ‘Emerald Dwarf’ was found to be significantly higher thanthree hybrid Bermudagrass cultivars, being 71.4% higher than ‘Tifgreen(328),’ 200% higher than ‘Tifdwarf,’ and 1100% higher than ‘Tifeagle’(see Table 5). FIG. 5 illustrates the rhizome formation of ‘EmeraldDwarf’ in native clay soil. FIGS. 6-9 illustrate the comparativeformation of relative rhizome and stolon formation of ‘Emerald Dwarf,’‘Tifgreen (328),’ ‘Tifdwarf,’ and ‘Tifeagle’ after 18 months of growthat putting greens height (0.125″-0.187″).

TABLE 5 Rhizomes vs. Stolons After 18 Months* Comparisons Among FourBermudagrass (Cynodon spp.) Genotypes Genotypes % Rhizomes % Stolons‘Emerald Dwarf’ 60 40 ‘Tifgreen (328)’ 35 65 ‘Tifdwarf’ 20 80 ‘Tifeagle’5 95 *Orientation of lateral stem growth in profiles removed fromreplicate plots maintained under putting greens maintenance, withsamples taken 18 months after planting. HOC was 0.125 April-October,0.157 November-March. Means of four replications assessed November 2000.Shoot Density

The shoots with leaves originate from the nodes along the lateral stems,from both stolons and rhizomes. A detailed, quantitative assessment wasmade of the shoot density. A particular concern for Bermudagrass greensis maintaining adequate shoot density at increasingly lower heights.With the improvements in equipment and increasing sophistication ofgolfers, it is now common to find greens regularly mowed at ⅛″. At thisheight adequate shoot density becomes critical to prevent sunlight fromreaching the surface of the soil which will cause algae to grow on thesurface. When shoot density is not adequate, weed invasion also becomesmore of problem. A concern with the Ultradwarf Bermudagrasses is thatthese cultivars have such high shoot densities that they requiredextensive cultivation to perform well long term. This extensivecultivation has been difficult for many superintendents to accomplishbecause it involves repeated disruption of play. ‘Emerald Dwarf’ hasbeen found to have a shoot density which is high but not excessive after18 months, with a 50% greater density than ‘Tifgreen (328),’ 4.3%greater density than ‘Tidwarf,’ and 25% lower density than ‘Tifeagle.’This is shown by Table 6A below. FIG. 10 illustrates comparative plugsof the four cultivars.

TABLE 6A Shoot Density After 18 Months* Comparisons Among FourBermudagrass (Cynodon spp.) Genotypes Genotypes Shoot Density (per in²)‘Emerald Dwarf’ 96 ‘Tifgreen (328)’ 64 ‘Tifdwarf’ 92 ‘Tifeagle’ 128*Number of shoots per in² in samples removed from replicate plotsmaintained under putting greens maintenance, with samples taken 18months after planting. HOC was 0.125 April-October, 0.157November-March. Means of four replications assessed November 2000.

A second test was done on shoot density 30 months after planting. Again,‘Emerald Dwarf’ has been found to have a midrange shoot density after 30months, with a 7.3% greater density than ‘Tifdwarf,’ and 21.4% lowerdensity than ‘Tifeagle.’ This is shown by Table 6B below. FIG. 11illustrates comparative plugs of ‘Emerald Dwarf,’ ‘Tifdwarf,’ and‘Tifeagle.’

TABLE 6B Shoot Density After 30 Months* Comparisons Among ThreeBermudagrass (Cynodon spp.) Genotypes Genotypes Shoot Density (per in²)‘Emerald Dwarf’ 88 ‘Tifdwarf’ 82 ‘Tifeagle’ 112 *Number of shoots perin² in samples removed from replicate plots maintained under puttinggreens maintenance, with samples taken 30 months after planting. HOC was0.125 April-October, 0.157 November-March. Means of four replicationsassessed October 2001.Rooting Depth

A detailed, quantitative assessment was made of the rooting depth.‘Emerald Dwarf’ has been found to have a comparatively greater rootdepth after 30 months, with a 49.7% greater depth than ‘Tifdwarf,’ and136.9% greater depth than ‘Tifeagle.’ This is shown by Table 7 below.FIG. 12 illustrates comparative root depths of the three cultivars after30 months at putting greens height (0.125″-0.187″).

TABLE 7 Root Depth After 30 Months* Comparisons Among Three Bermudagrass(Cynodon spp.) Genotypes Genotypes Root Depth (cm) ‘Emerald Dwarf’ 28.9‘Tifdwarf’ 19.3 ‘Tifeagle’ 12.2 *Measurement of depth of deepest rootsin 11.4 cm² column samples removed from replicate plots maintained underputting greens maintenance, with samples taken 30 months after planting.HOC was 0.125 April-October, 0.157 November-March. Means of fourreplications assessed October 2001.Root Mass

A detailed, quantitative assessment was made of the root mass. ‘EmeraldDwarf’ has been found to have a comparatively greater root mass after 30months, with a 525% greater total root mass than ‘Tifeagle,’ and 108.3%greater total root mass than ‘Tifdwarf.’ This is shown by Table 8 below.As shown by the table, ‘Emerald Dwarf’ had a significantly higher rootmass at each sample depth.

TABLE 8 Root Mass After 30 Months* Comparisons Among Three Bermudagrass(Cynodon spp.) Genotypes Genotypes 0-3″ (mg) 3-6″ (mg) >6″ (mg) Total(mg) ‘Emerald Dwarf’ 241 153 131 525 ‘Tifdwarf’ 154 83 15 252 ‘Tifeagle’72 12 0 84 *Weight of roots at three different depths in 11.4 cm² columnsamples removed from replicate plots maintained under putting greensmaintenance, with samples taken 30 months after planting. HOC was 0.125April-October, 0.157 November-March. Means of four replications assessedOctober 2001.Rhizome Production

A detailed, quantitative assessment was made of the rhizome productionof three Bermudagrass cultivars under putting green maintenance.‘Emerald Dwarf’ has been found to have a comparatively greater rhizomeproduction after 30 months, with a 57.9% greater rhizome production than‘Tifdwarf.’ ‘Tifeagle’ showed not measurable rhizome production in thattime period. This is shown by Table 9 below. FIGS. 13-15 illustratecomparative rhizome production of ‘Emerald Dwarf’ and ‘Tifdwarf’ after30 months at putting greens height (0.125″-0.187″).

TABLE 9 Rhizome Production After 30 Months* Comparisons Among ThreeBermudagrass (Cynodon spp.) Genotypes Genotypes Rhizome Production (mg)‘Emerald Dwarf’ 240 ‘Tifdwarf’ 152 ‘Tifeagle’ — *Weight of viablelateral stems growing 1 cm or deeper below the surface in 11.4 cm²column samples removed from replicate plots maintained under puttinggreens maintenance, with samples taken 30 months after planting. HOC was0.125 April-October, 0.157 November-March. Means of four replicationsassessed October 2001.Depth of Deepest Rhizomes

A detailed, quantitative assessment was made of the depth if the deepestrhizomes of three cultivars under putting green maintenance. ‘EmeraldDwarf’ has been found to have a comparatively greater deepest rhizomedepth after 30 months, with a 126.7% greater depth than ‘Tifdwarf.’‘Tifeagle’ showed no measurable rhizome production in that time period.This is shown by Table 10 below. FIGS. 16-18 illustrate comparativerhizome depths of the three cultivars after 30 months at putting greensheight (0.125-0.187″).

TABLE 10 Depth of Deepest Rhizomes After 30 Months* Comparisons AmongThree Bermudagrass (Cynodon spp.) Genotypes Genotypes Depth (cm)‘Emerald Dwarf’ 3.4 ‘Tifdwarf’ 1.5 ‘Tifeagle’ — *Depth of deepest viablelateral stems as measured from soil surface in 11.4 cm² column samplesremoved from replicate plots maintained under putting greensmaintenance, with samples taken 30 months after planting. HOC was 0.125April-October, 0.157 November-March. Means of four replications assessedOctober 2001.Deep Rhizome Development

Compared to the other known greens cultivars, and particularly whencompared to ultradwarf cultivars, the ‘Emerald Dwarf’ cultivar producessubstantially greater rhizomes. Some of the benefits of this growthhabit for application on a putting green are:

-   -   1. ‘Emerald Dwarf’ allows for better water infiltration because        the lateral stems are not stacked on the surface to form an        organic barrier but are distributed throughout the top inch or        more of the profile.    -   2. ‘Emerald Dwarf’ is much less prone to scalping because the        stems are down in the soil out of reach of the mower. This        allows for architectural features such as more sever slopes that        would create difficulties for more stoloniferous cultivars.    -   3. The surface created is more inherently firm, which is a major        component of putting surface ball-roll speed.    -   4. ‘Emerald Dwarf’ has a reduced topdressing requirement because        there is less need for dilution of the stem biomass.    -   5. ‘Emerald Dwarf’ has a reduced aerification requirement        because there is less organic matter creation due to less stem        biomass at the surface.    -   6. ‘Emerald Dwarf’ can withstand infrequent, deep verticutting        because the mower is supported on a firm surface as opposed to a        bed of lateral stems as is the case with a highly stoloniferous        grass.    -   7. Because there is less thatch creation due to the lesser stem        accumulation, the grass can be managed with higher nitrogen        levels, resulting in more vigor, better recuperative potential,        dark-green turf color described by the R.H.S. Color Chart as        R.H.S. 138A, medium light green.    -   8. The turf created is more receptive to overseeding with cool        season grasses, including large-seeded species such as ryegrass.        Deep Rooting

Compared to the other known greens cultivars, and particularly whencompared to ultradwarf cultivars, the ‘Emerald Dwarf’ cultivar producessubstantially deeper roots. Some of the benefits of this growth habitfor application on a putting green are:

-   -   1. ‘Emerald Dwarf’ has better water uptake throughout the soil        profile. This allows for less frequent watering, particularly on        a perched water table design rootzone (such as USGA        Specification green).    -   2. ‘Emerald Dwarf’ has better nutrient uptake throughout the        rootzone profile. This makes granular fertilizer applications        more effective, reducing or eliminating the need for foliar        fertilizer applications.    -   3. ‘Emerald Dwarf’ will perform well in coarse sand rootzones        (such as USGA Specification green) because of the ability to        draw moisture from deep within the profile.    -   4. ‘Emerald Dwarf’ can better withstand poor irrigation water        quality because of the ability to water deeply and infrequently        which flushes the salts down through the rootzone.    -   5. ‘Emerald Dwarf’ is less prone to moisture stress, “hot        spots”, etc. because of the deeper rooting. This allows for        architectural features such as high mounds and more severe        slopes that would be difficult to manage with more shallow        rooted cultivars.        Overseeding and Transition

The University of California at Riverside Coachella Valley AgriculturalResearch Station evaluated warm-season turfgrasses for putting green usein the Coachella Valley. The grasses were established with stolons inearly April 2001, to a sand based putting green plot. The specificationsfor the construction of the simulated putting green followed thosecommonly used in recently constructed golf courses in the CoachellaValley. There were three replications of each grass chosen for the studyand the field study was arranged in a randomized block design. The sitewas managed through grow-in as is commonly performed in the local area.The specific management practiced was as follows:

-   -   -   Mowing height.—0.125 inch. The mowing height was reduced            slowly following establishment, over a 30-day period, to the            desired mowing height. The height was kept constant            throughout the calendar year, until overseeding.        -   Frequency.—Mowing was performed 6-7 times per week, skipping            Sunday if 6 times per week.        -   Mowing pattern.—The research area was mowed north and south            (length of grass plots) until plots filled together, than            the plot area was mowed at various directions (alter            direction) to eliminate the development of grain.        -   Clippings.—Removed throughout study.        -   Turf grain control.—An appropriate groomer on the mower was            used as needed to prevent turf grain formation. Particular            attention to grain control was paid when the grass was            growing vigorously during the late spring, summer, and early            autumn.        -   Fertilization.—The study area was fertilized at the annual            rate of 5 lbs N/1000 sq ft; 1.6 lbs P; and 2.5 lbs K using a            15-5-8 fertilizer. The rate of 0.5 lbs N/100 sq ft was            applied in mid-March to early April as a spring bump, then            0.3 lbs N/1000 sq ft per 3 weeks. In February 2003, the            three-week application was increased in rate to 0.4 lbs            N/1000 sq ft. The fertilizer was applied in two directions            at each application time.        -   Cultivation-verticutting.—During spring, summer and early            autumn (May 1- October) light verticutting was performed            every 3 weeks. Attention was given to prevent damage to turf            if the grass was not growing vigorously.        -   Topdressing.—A light sand topdressing was applied 1 week            after vertical mowing, May-October.        -   Aerification.—A ⅜-inch hollow tine aerifier was used to            remove cores in early October 2002 in association with the            overseeding operation.        -   Overseed process.—Overseeding was done on Oct. 10, 2002. It            was preceded with a vigorous vertical mowing with the            organic matter removed. The green was aerified, cores            allowed to dry and then shattered. Sand from the cores was            dragged and surface material removed from the green. The            green was overseeded with a mix of perennial ryegrass and            rough stalk bluegrass. CBSII blend of perennial ryegrass            (‘Brightstar II’ at 33.12%, ‘Quickstart’ at 32.73%, and            ‘Charger II’ at 32.71%) was overseeded at the rate of 20            lbs/1000 sq ft. ‘Winterplay’ Poa trivialis was overseeded at            the rate of 8 lbs/1000 sq ft and followed by weekly            overseeding at the rate of 1 lb for two weeks (10 lbs            seed/1000 sq ft total). A sand topdressing followed the            primary overseeding operation. The overseeded grasses were            germinated with frequent irrigation until seedlings were            established.        -   Data collected.—Visual recordings of turf performance were            collected, usually every two weeks, throughout the study            period. Grass establishment, quality, color, and plot            uniformity were rated on a 1-9 scale with 9 representing the            highest level of each characteristic and 1 representing the            lowest or absence of the characteristic. Percentage of            warm-season grass was recorded on a 0-100% scale. The data            were grouped into time periods of similar performance based            on maturity and time of year so the results are presented an            analysis performed on data from those time periods. An            analysis of variance was performed on collected results from            the randomized complete block designed study. Repeated            measures analysis was used with dates treated as the            repeated factor within the time period of analysis.            Significant difference was determined by Fishers Protected            LSD at the 0.05 level of probability. All grasses completely            covered the plots by September, following the April            establishment. The study was overseeded in October 2002.            Color and quality of the overseeded swards were evaluated            for play season (November-May) and for the transition season            of June-July when the cool-season grasses died out and the            warm-season achieved cover and dominated the sward. The            results, shown in Table 11 below, indicate that ‘Emerald            Dwarf’ has comparatively better color and higher quality            than the measured ultradwarf turfgrass.

TABLE 11 Overseeding Color and Quality* Comparisons Between ‘EmeraldDwarf’ and Ultradwarf Bermudagrasses November November June 2003- June2003- 2002-May 2002-May July 2003 July 2003 Genotypes 2003 Color 2003Quality Color Quality ‘Emerald 6.6 6.5 6.6 6.2 Dwarf’ Ultradwarf 6.5 6.46.5 4.8 Bermuda- grasses** *Color and quality of overseeded puttinggreens grasses November 2002 through July 2003. Ratings: 1 = poorquality/light color; 9 = excellent quality/dark green color. **Compositescore of ratings of four ultradwarf Bermudagrasses (‘Champion,’‘Floradwarf,’ ‘Miniverde,’ ‘Tifeagle’), performed October 2003 atUniversity of California Riverside Coachella Valley AgriculturalResearch Station

Uniformity ratings, which account for the way the warm-season andcool-season overseeded grass interacted in the study, were alsoevaluated and the results are presented in Table 12, and the percentageof warm-season grass during the transition period in Table 12. It can beobserved that the uniformity ratings do not differ much during April-Maywhen the cool-season overseeded mix was present. The results, shown inTables 12-13 below, indicate that ‘Emerald Dwarf’ has better uniformityand a higher percentage of Bermudagrass during the transition periodthan the ultradwarf grasses.

TABLE 12 Uniformity During Transition* Comparisons Between ‘EmeraldDwarf’ and Ultradwarf Bermudagrasses April-May June-July AugustGenotypes 2003 2003 2003 ‘Emerald Dwarf’ 6.4 6.6 6.7 UltradwarfBermudagrasses** 6.4 4.9 5.4 *Uniformity of putting green turfs leadingup to and during transition of overseeded putting green grasses, April2003 through July 2003.. Ratings: 1 = non-uniform; 9 = uniform surface.**Composite score of ratings of four ultradwarf Bermudagrasses(‘Champion,’ ‘Floradwarf,’ ‘Miniverde,’ ‘Tifeagle’), performed October2003 at University of California Riverside Coachella Valley AgriculturalResearch Station

TABLE 13 Percentage of Bermudagrass* Comparisons Between ‘Emerald Dwarf’and Ultradwarf Bermudagrasses April June July August Genotypes 2003 20032003 2003 ‘Emerald Dwarf’ 51.7 70.0 83.3 90.0 UltradwarfBermudagrasses** 43.3 42.9 67.5 86.7 *Percent coverage of Bermudagrassleading up to and during transition of overseeded putting greens grassesApril 2003 through August 2003. **Composite score of ratings of fourultradwarf Bermudagrasses (‘Champion,’ ‘Floradwarf,’ ‘Miniverde,’‘Tifeagle’), performed October 2003 at University of CaliforniaRiverside Coachella Valley Agricultural Research StationDetailed Characteristics

A detailed description of the new and distinct genotype of hybridBermudagrass named ‘Emerald Dwarf’ includes:

-   -   1. a unique relative ratio of rhizome and stolon production,        with a ratio of about 60% rhizomes to 40% stolons;    -   2. a unique rooting depth, on the order of 28-29 cm after 30        months, with rhizomes growing deeply in the profile and        distributed throughout the first 1″ of the profile, rather than        being stacked near the surface;    -   3. a shoot density higher than ‘Tifdwarf,’ but lower than        high-density ultradwarfs, that produces a uniform, high-quality        turf surface with relatively little thatch accumulation compared        to high-density cultivars, where the shoot density is maintained        in the fall;    -   4. the internode length of stolons is on the order of 14-15 mm;    -   5. the leaf width is on the order of 1.3 mm under very close        mowing;    -   6. a total root mass on the order of 525 mg after 30 months,    -   7. the leaves are folded in the bud shoot;    -   8. the leaf blades are flattened to v-shaped in cross-section,        keeled, and gradually tapering to an acute point;    -   9. the ligule at the junction of the leaf blade and leaf sheath        is a fringe-of-hairs;    -   10. there is no auricle present;    -   11. the collar on the opposite side from the ligule is a        continuous, narrow band;    -   12. the lateral stems, both stolons and rhizomes, branch        profusely at the nodes;    -   13. each node-cluster produces three leaves;    -   14. the roots originate from nodes and are fine, fibrous, and        dense;    -   15. the unmowed shoot growth height is on the order of 2 inches        (50 mm); and    -   16. the seeds produce small vegetative shoots while they are        attached to the seedhead. (See FIG. 20).

These characteristics produce greens that:

-   -   1. keep better infiltration;    -   2. are not prone to scalping;    -   3. do not require a great deal of topdressing;    -   4. do not require extensive aerification;    -   5. do not require frequent watering;    -   6. can withstand infrequent, deep verticutting;    -   7. can be managed with higher nitrogen, resulting in more vigor,        better recuperative growth;    -   8. will readily accept overseeding;    -   9. will perform well in coarse sand rootzones;    -   10. can withstand poor water quality; and    -   11. are less prone to stresses.

1. A new and distinct Bermudagrass plant, substantially as herein shownand described, distinguished by greater rhizome development and rootingdepth in conjunction with low surface stolon development, yet havingshoot density sufficient to enable it to withstand mowing at very lowputting green heights.